PROG SIGNAL LEDs do not turn on - They do not show signal strength.
Initial documentation for the MTC-LAT1 builds incorrectly describes the PROG SIGNAL LED behavior as they were defined for the MTC-H5 models. The MTC-H5 is preloaded with an application that controlled the LEDs for signal strength. The MTC-LAT1 does not have the capability to add an application into the MTC-LAT1 cellular modules so it cannot be programmed to match the function that exists in MTC-H5. These LEDs can only be controlled via AT commands and are left for the customer to control, if desired. To make use of these LEDs you can control them from the host system using the AT#GPIO command (see AT command manual for details). The LEDs map to particular GPIO on the radio: * GPIO2: Controls the LED with a single bar above it * GPIO3: Controls the LED with two bars above it * GPIO4: Controls the LED with three bars above it AT command examples: AT#GPIO=2,0,1 - Turn LED 1 OFF AT#GPIO=2,1,1 - Turn LED 1 ON AT#GPIO=3,0,1 - Turn LED 2 OFF AT#GPIO=3,1,1 - Turn LED 2 ON AT#GPIO=4,0,1 - Turn LED 3 OFF AT#GPIO=4,1,1 - Turn LED 3 ON